Traction vehicles such as, for example, locomotives, employ electric traction motors for driving wheels of the vehicles. In some of these vehicles, the motors are alternating current (AC) motors whose speed and power are controlled by varying the frequency and the voltage of AC electric power supplied to the motors. Commonly, the electric power is supplied at some point in the vehicle system as DC power and is thereafter converted to AC power of controlled frequency and voltage amplitude. The electric power may be derived from an on-board alternator driven by an internal combustion engine or may be obtained from a wayside power source such as a 3rd rail or overhead catenary.
Inefficiency in the process of controlling the inverters that produce AC power can adversely affect the efficiency of the entire locomotive. In general, there is a need for a more efficient system and method for controlling the firing of inverters in power systems.